1. Field of the Invention
The present invention relates to a saddle-type vehicle equipped with an automatic transmission.
2. Description of Related Art
Some known saddle-type vehicles are equipped with a transmission having a plurality of gears and a clutch that is engaged or disengaged at gear shift. Such vehicles may also have a clutch actuator for engaging or disengaging the clutch and a shifting actuator for actuating the gear-shift operation of the transmission so that the application and release of the clutch and the gear shift are automatically performed (see JP-A-2003-320861).
The clutch actuator and the shifting actuator are controlled to synchronize with each other. Thus, the clutch on-off operation and the gear-shift operation of the transmission are performed at an appropriate timing. Accordingly, if one of the actuators fails, it is impossible to synchronize the clutch on-off operation and the gear-shift operation of the transmission, thereby disabling gear shift and preventing the vehicle from being driven. However, even with a failed actuator, the rider will find it convenient if he/she can drive to a repair shop or the like.
Another known saddle-type vehicle uses the clutch actuator and the shifting actuator in common; that is, the clutch on-off operation and the gear-shift operation of the transmission are performed with one actuator. In this type of saddle-type vehicle, the clutch on-off operation and the gear-shift operation of the transmission are synchronized only by rotating the shift shaft. Accordingly, even if the actuator fails, shift change is possible provided that the shift shaft can be forced to rotate by some means. Consequently, this type of saddle-type vehicle can be driven at a desired shift position (for example, the first gear or the second gear) even with the actuator failed.
JP-A-2001-124203 discloses a motorcycle in which one of a motor change mode for driving the shift shaft by a motor and a manual change mode for manually driving the shift shaft can be selected. In this type of motorcycle, the shift shaft can be manually rotated by switching to the manual change mode, so that it can be driven even with a failed motor.
Thus, the saddle-type vehicle of JP-A-2003-320861 cannot be driven if the actuator fails. On the other hand, the motorcycle of JP-A-2001-124203 needs another mechanism for switching the mode, so that the power unit structure is complicated and large.